The group of six arrived in Cabo San Lucas, Mexico via private on Friday and have been photographed sunbathing together on lounge chairs at a resort, walking along the beach and having dinner.
This is the first time Kourtney has been seen publicly with Sofia, who began dating Scott more than a year ago and who has spent a lot of time with Mason, 9, Penelope, 6, and Reign, 4.
"The first day they all hung out together with the kids at the beach," a source told E! News. "Kourtney, Sofia and Scott were all chatting and enjoying the day. Scott was in the middle of Sofia and Kourtney and they were lined up on chaise lounges. Scott got up to play with the kids and Kourtney and Sofia were chatting."
"They look like they are on very good terms and there wasn't any tension," they finished.
Scott even uploaded a photo of all three of them sunbaking on his Instagram, writing, "
Talk about co-parenting goals.